staying safe in earthquakes

protecting yourself in an earthquake

If you live in an earthquake zone, there are many things you can do to protect yourself. You must protect your home. Your household must be ready to live independently for a few days. It may take emergency services that long to get to everyone. Before an Earthquake: Make sure the floor, walls, roof, and foundation are all well attached to each other. Have an engineer evaluate your house for structural integrity. Bracket or brace brick chimneys to the roof. Be sure that heavy objects are not stored in high places. Move them to low places so that they do not fall. Secure water heaters all around and at the top and bottom. Bolt heavy furniture onto walls with bolts, screws, or strap hinges. Replace halogen and incandescent light bulbs with fluorescent bulbs to lessen fire risk. Check to see that gas lines are made of flexible material so they do not rupture. Any equipment that uses gas should be well secured. Everyone in the household should know how to shut off the gas line. A wrench should be placed nearby for doing so. Prepare an earthquake kit with at least three days supply of water and food. Include a radio and batteries. Place flashlights all over the house so there is always one available. Place one in the glove box of your car. Keep several fire extinguishers around the house to fight any small fires that break out. Be sure to have a first aid kit. Everyone in the household who is capable should know basic first aid and CPR. Plan in advance how you will evacuate your property and where you will go. Do not plan on driving, as roadways will likely be damaged. During the Earthquake: If you are in a building, drop to the ground, get beneath a sturdy table or desk, cover your head, and hold on. Stay away from windows and mirrors since glass can break and fall on you. Stay away from large furniture that may fall on you. If the building is structurally unsound, get outside as fast as possible. Run into an open area away from buildings and power lines that may fall on you. If you are in a car, stay in the car and stay away from structures that might collapse like overpasses, bridges, or buildings. After the Earthquake: Be aware that aftershocks are likely. Avoid dangerous areas, like hillsides, that may experience a landslide. Turn off water, gas lines, and power to your home. Use your phone only if there is an emergency. Many people with urgent needs will be trying to get through to emergency services. Be prepared to wait for help or instructions. Assist others as necessary.

damage from earthquakes

Earthquake magnitude affects how much damage is done in an earthquake. A larger earthquake damages more buildings and kills more people than a smaller earthquake. But thats not the only factor that determines earthquake damage. The location of an earthquake relative to a large city is important. More damage is done if the ground shakes for a long time. The amount of damage also depends on the geology of the region. Strong, solid bedrock shakes less than soft or wet soils. Wet soils liquefy during an earthquake and become like quicksand. Soil on a hillside that is shaken loose can become a landslide. Hazard maps help city planners choose the best locations for buildings (Figure 7.38). For example, when faced with two possible locations for a new hospital, planners must build on bedrock rather than silt and clay.

mexico city 1985

The 1985 Mexico City earthquake measured magnitude 8.1. The earthquake killed at least 9,000 people, injured 30,000 more, and left 100,000 people homeless. It destroyed 416 buildings, and seriously damaged 3,000 other buildings. The intense destruction was due to the soft ground the city is built on. Silt and clay fill a basin made of solid rock. In an earthquake, seismic waves bounce back-and-forth off the sides and bottom of the rock basin. This amplifies the shaking. The wet clay converts to quicksand (Figure 7.39). Many buildings were not anchored to bedrock. They settled into the muck. This caused enormous damage. Water, sewer, and electrical systems were destroyed, resulting in fires. Acapulco was much closer to the epicenter, but since the city is built on bedrock it suffered little damage.

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anchorage alaska 1964

The amount of damage depends on the amount of development in the region. The 1964 Great Alaska Earthquake, near Anchorage, was the largest earthquake ever recorded in North America. The gigantic quake had a magnitude of 9.2. The earthquake lasted for several minutes and the ground slipped up to 11.5 meters (38 feet). An area of 100,000 square miles (250,000 square km) was affected. The ground liquefied, causing landslides (Figure 7.40). The earthquake occurred at a subduction zone, and large tsunami up to 70 meters (20 feet) high were created. Despite the intensity of the earthquake, only 131 people died. Most deaths were due to the tsunami. Property damage was just over $300 million ($1.8 billion in 2007 U.S. dollars). The reason there was such a small amount of damage is that very few people lived in the area (Alaska had only been a state for five years!). A similar earthquake today would affect many more people.

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earthquakesafe structures

Buildings must be specially built to withstand earthquakes. Skyscrapers and other large structures built on soft ground must be anchored to bedrock. Sometimes that bedrock is hundreds of meters below the ground surface!

buildings

Building materials need to be both strong and flexible. Small structures, like houses, should bend and sway. Wood and steel bend. Brick, stone, and adobe are brittle and will break. Larger buildings must sway, but not so much that they touch nearby buildings. Counterweights and diagonal steel beams can hold down sway. Buildings need strong, flexible connections where the walls meet the foundation. Earthquake-safe buildings are well connected (Figure Steel or wood can be added to older buildings to reinforce a buildings structure and its connections (Figure 7.42). Elevated freeways and bridges can also be reinforced so that they do not collapse. Important structures must be designed to survive intact.

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avoiding fire

One of the biggest problems caused by earthquakes is fire. Fires start because earthquakes rupture gas and electrical lines. Water mains may break. This makes it difficult to fight the fires. The shapes of pipes can make a big difference. Straight pipes will break in a quake. Zigzag pipes bend and flex when the ground shakes. In San Francisco, water and gas pipelines are separated by valves. Areas can be isolated if one segment breaks.

making choices

Strong, sturdy structures are expensive to build. Communities must decide how safe to make their buildings. They must weigh how great the hazard is, what different building strategies will cost, and how much risk they are willing to take.

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instructional diagrams

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questions

Much of the damage caused by earthquakes is done by

a. fires.

b. tsunamis.

c. landslides.

-->  d. all of the above

Which of the following hardly ever kills anyone in an earthquake?

a. structures falling

-->  b. ground shaking

c. fire

d. tsunami

Earthquake-safe construction methods include

a. making buildings out of stone.

-->  b. anchoring buildings to bedrock.

c. making buildings without foundations.

d. all of the above

Not too many people died in the Great Alaska Earthquake in 1964 because

-->  a. few people lived in the area

b. it was not a large quake

c. the ground was so solid that the shock was absorbed.

d. none of these

The Great Alaska Earthquake occurred

a. near the capital city of Juneau.

b. where many people lived.

-->  c. at a subduction zone.

d. in 2004.

If you want to be safe in an earthquake, build your house on

a. soft sediments that absorb shock

b. sediments that will undergo liquefaction

-->  c. solid bedrock

d. any type of ground is fine, just build a solid house

To keep gas lines and water mains from breaking in an earthquake,

a. make them completely solid so that they dont break.

b. put them above ground so that they dont break.

c. zigzag the pipes so that they bend to absorb ground shaking.

-->  d. b c

Structures that reduce how much buildings sway during an earthquake include

a. diagonal steel beams.

b. heavy slate roofs.

c. counterweights.

-->  d. two of the above

Steel is a good building material for earthquake zones because steel

-->  a. bends without breaking.

b. is very light in weight.

c. resists shaking.

d. is very rigi

Which of the following is something that you should NOT do during an earthquake.

-->  a. Take an elevator to the ground floor so that you can run outside.

b. Stay away from things that can break or fall on you.

c. Dive underneath a sturdy piece of furniture.

d. Run to an open area if you are outside.

If you live in a place where the risk of earthquakes is high, you should

a. keep heavy objects near the floor.

b. prepare an emergency kit.

c. use fluorescent light bulbs.

-->  d. all of the above

If you are in a car when an earthquake occurs, you should

a. run into the nearest building.

b. get out of the car and drop to the ground.

-->  c. stay in the car and away from buildings.

d. stay in the car and park under an overpass.

solid material that shakes less than soil during an earthquake

a. liquefy

b. magnitude

-->  c. bedrock

d. landslide

e. hazard map

f. fire

g. quicksand

earthquake risk that may occur because gas lines break when the ground shakes

a. liquefy

b. magnitude

c. bedrock

d. landslide

e. hazard map

-->  f. fire

g. quicksand

tool for showing the likelihood of strong earthquakes in a region

a. liquefy

b. magnitude

c. bedrock

d. landslide

-->  e. hazard map

f. fire

g. quicksand

In case of an earthquake, a one day supply of food and water is enough for a family.

a. true

-->  b. false

sudden collapse of a hillside that may occur during an earthquake

a. liquefy

b. magnitude

c. bedrock

-->  d. landslide

e. hazard map

f. fire

g. quicksand

Large buildings can be placed on rollers so that they move as the ground moves.

-->  a. true

b. false

one of many factors that affect how much damage is done by an earthquake

a. liquefy

-->  b. magnitude

c. bedrock

d. landslide

e. hazard map

f. fire

g. quicksand

to change to a liquid

-->  a. liquefy

b. magnitude

c. bedrock

d. landslide

e. hazard map

f. fire

g. quicksand

The largest recorded earthquake was 12.3 on the Richter Scale

a. true

-->  b. false

material that forms when wet soil shakes and liquefies in an earthquake

a. liquefy

b. magnitude

c. bedrock

d. landslide

e. hazard map

f. fire

-->  g. quicksand

The projected Mercalli Intensity scale for a future earthquake is used by city planners in earthquake

-->  a. true

b. false

Elevated freeways can be retrofitted for earthquakes.

-->  a. true

b. false

All earthquake damage is caused by the ground shaking.

a. true

-->  b. false

A stronger earthquake always causes more damage than a weaker earthquake.

a. true

-->  b. false

An earthquake always causes more deaths in cities closer to the epicenter.

a. true

-->  b. false

The Great Alaska Earthquake had a magnitude greater than 9 on the Richter scale.

-->  a. true

b. false

Most deaths in the Great Alaska Earthquake were due to the tsunami.

-->  a. true

b. false

In earthquake zones, building materials should be strong and rigid.

a. true

-->  b. false

Buildings should be constructed so they do not bend and sway in an earthquake.

a. true

-->  b. false

If you are inside when an earthquake strikes, you should get beneath a sturdy table or desk.

-->  a. true

b. false

If you are outside when an earthquake strikes, you should run to an open area away from buildings and

-->  a. true

b. false

In earthquake zones, heavy furniture should be attached securely to walls.

-->  a. true

b. false

diagram questions

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